This song was developed by Garcia, Crosby and Kantner at the sessions that were captured on the "PERRO tapes" in January 1971. Four versions of Mountain Song are appear on these tapes. The musicians at the PERRO sessions included David Crosby, Jerry Garcia, Paul Kantner, Graham Nash, Phil Lesh, Bill Kreutzmann, Mickey Hart, Grace Slick and Jorma Kaukonen.

Of these musicians only Kantner and Grace Slick feature on the 1983 PERRO album. Kantner's dedication for Mountain Song on the album though reflects it's origin;

David C, Jerry G, Graham N, Grace S, David F, Billy K and Mickey H, and to one summer when all our schedules almost didn't conflict.

On the album the writing credits for the song are given as Kantner and Garcia.

Parts of this piece have been incorporated into the song Mountain Town.